Monsoons are paradise months, that if you are a monsoon traveller it is an added benefit. Here are some monsoon spots to visit in India especially now. Wayanad
Munnar
Alapuzha
Kumarakom in Kerala
Coorg
Kudremukh Chikmagalur
Gokarna
Kabini in Karnataka
Mahabaleshwar Matheran
Panchgani
Lonavala in Maharashtra
Meghalaya Assam
Sikkim Gangtok in north east
Kindly do a rain check before travelling for in many places rains are too heavy.
People looking to do treks then there in no best place other then Maharashtra
You can do trek at Lohegad, Visapur, Singhad Fort, Purandar Fort(well maintained by army and trek closes before 230pm) etc